1. Field of the Invention
The present invention relates to a light source unit which utilizes laser for a light source and a projector which includes the light source unit.
2. Description of the Related Art
In these days, data projectors are used in many cases as image projection apparatuses which project images including video images shown on screens of personal computers on to a screen, and the data projectors further read out image data or dynamic image data stored in memory cards for projection on to the screen. These projectors are such that light emitted from a light source is concentrated on a micromirror device called a DMD (Digital Micromirror Device) or a liquid crystal plate for display of a color image on the screen.
In projectors of the type described above, conventionally, projectors using a high-intensity discharge lamp as a light source have been the mainstream of projectors. In recent years, however, there have been made many developments and proposals on light source units which utilize as a light source a light emitting diode or a laser diode, or devices utilizing organic EL technology or luminescence technology using luminescent materials. For example, a light source unit described in Japanese Unexamined Patent Publication No. 2004-341105 (JP-A-2004-341105) includes a luminescent wheel which is made up of a disc-shaped transparent base material on which a luminescent material layer is disposed and a solid-state light source which emits ultraviolet light, and the luminescent wheel is described as converting ultraviolet light received into visible light. In the light source unit described in JP-A-2004-341105, ultraviolet light is shone on to the luminescent material layer formed on the luminescent wheel as excitation light, so that luminescent light having red, green and blue wavelength bands can be emitted.
However, since the light emitting efficiency of the red luminescent material is remarkably lower than those of the other luminescent materials, there has been caused a problem that the luminance of red becomes insufficient.